1. Field of the Invention
The present invention is directed to underground heat exchange systems and to apparatus and methods for installing a loop of pipe in a hole in the earth.
2. Description of Related Art
The prior art discloses a variety of systems and apparatuses for installing ground heat exchange pipe loops in a wellbore. In certain prior art systems a wellbore is drilled, e.g. a drill rig drills a vertical four to four-and-a half inches in diameter hole, e.g. to a depth of about 250 feet. In one aspect a single piece of polyethylene pipe attached to a sinker bar is introduced into the hole and then pulled out of the hole manually while grout is introduced into the hole. In another aspect a polyethylene pipe loop is pushed to the bottom of the hole by a wire-line retrievable sinker bar. When the sinker bar is removed, a series of 2 inch PVC tremmie pipes are screwed together and lowered to the bottom of the hole. A bentonite clay mixture called grout is then batch mixed at the surface and pumped into the tremmie pipe. As each batch is pumped into the hole the tremmie pipe string is raised and one 20 foot section of pipe is removed from the hole and laid on the ground. When the hole is filled to the surface and all of the tremmie pipe has been removed the drill rig is moved to another drilling position, usually at least 15 feet away. When all of the pipe loops have been installed (e.g. one loop for each ton of heating and cooling equipment), the drill rig is removed from the site. A trench (e.g. about four feet deep) is then dug to contain pipes that interconnect all of the pipe loops. Once the trenching is completed the connecting pipe is laid into the trench and heat fused to each of the vertical pipe loops. The connection pipe is then pressure tested and buried and becomes a circulating manifold which carries water between the earth and a heat pump located within an adjacent building. The trenching and manifolding of the surface pipe typically takes as much time as the wellbore drilling and pipe installation.
The prior art discloses numerous in-ground heat exchanger systems (e.g. see U.S. Pat. Nos. 5,244,037; 5,261,251); and grouting systems (see, e.g. U.S. Pat. No. 5,435,387).